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In Reply to: RE: Why More Power? posted by pictureguy on July 07, 2015 at 12:40:13
Could the need for more power be related to 'dynamic headroom'?
http://www.axiomaudio.com/dynamicheadroom
Follow Ups:
More power indeed gives you more dynamic headroom but the OP's question is surely whether bigger drivers implies more power is needed.
Andy
Sure, more power AND larger drivers may imply more headroom or simply that the panel has higher upper power limits with the SAME sensitivity. Yes, it may 'play louder'.
I know voice coil / cone drivers suffer from dynamic compression where increase of power in doesn't result in more output, but does result in distortion and other non-linear behavior.
Maybe panels have a similar mode?
Too much is never enough
Work is required for a driver to perform its job. Larger drivers require more work (than do smaller drivers).
| Work is required for a driver to perform its job. Larger drivers require more work (than do smaller drivers).
But the efficiency of coupling the motion of those drivers into acoustic output, especially at lower frqeuencies, goes up as well.
You convinced me, hereafter I'm only going to be listening to my Tympani IVAs powered by an Onkyo TX8511 (which BTW does a fairly decent job with my MMGs).
From crutchfield.com:
"For high-end stereo sound at a remarkably down-to-earth price, check out this impressive receiver from Onkyo! Boasting 100 watts x 2 channels of clean, high-current power, the TX-8511 is a dream come true for music lovers everywhere. Onkyo is famous the world over for their low-impedance amplifier design — and a look inside this model reveals why.
Onkyo pays attention to detail in every aspect of construction. The transformer: oversized and shielded for maximum power capacity and stability, and minimum hum. The filter capacitor: oversized for clean sound during your music's most demanding dynamic peaks. The cast aluminum heat sink: oversized for efficient heat dissipation, and thus longer life from your receiver. Discrete outputs: designed to run cooler, and to keep your music cleaner, under high-volume, low-impedance conditions. Anti-resonant chassis and aluminum front panel: highly rigid to fight distortion-causing resonance."
If you highpassed the input to the amplifier to match the frequency response of the MMG's you'd probably not need more power, all else being equal (which isn't the case---Maggies have also generally increased in efficiency over time).But obviously people want to use the big drivers, to give substantial output at substantially lower frequencies, so the power needed to achieve desired and feasible results is of course higher than using small drivers to give less. But still less power than trying to make small drivers give the same SPL at the same low frequency!
Otherwise we could use tweeters and headphone drivers full range and we don't.
Anyway, I was thinking more of box-speakers, where higher efficiencies for towers with larger woofers than smaller standmounts are normal.
Edits: 07/08/15
EFFICIENCY, as distinguished from Sensitivity, of speakers, is Under 1% except perhaps in the MOST sensitive speakers.
A speaker with 1% efficiency would be OVER 110db/watt/meter
Too much is never enough
I'm considering the physical equation for 'Work', W = F X D. (Isn't work required to move a Maggie's diaphragm/membrane?)
If a listener attempts driving a 20.7 with some 'garden type' amplifier, integrated or not, which is more than merely satisfactory to listen to a MMG, what is likely to happen, (even if somehow their impedances could be made the same, 'autoformer')? Perhaps one should substitute a 3.X for the 20.7, and just to screw with your mind, try replacing that MMG with a Tympani IIIB.
Everyone knows the result (as even do I), so what's its electrical or physical basis? Since I don't pretend to know the answer, I'll then ask that question in answer your original question.
All things being equal, larger drivers SHOULD require more 'work' = energy input to do their 'job'.
However, it would appear that, at least for the panels I originally mentioned, the sensitivity is the same, or so close as to be insignificant. That tells me that the same amp used across the line will produce the same SPL. or very, very close.
That's what started off my quesitoning.
Too much is never enough
This work, energy, power scenario is the source of my confusion. It shouldn't come as any surprise that an amp capable of driving a 8 ohm Maggie to window shattering levels can't get a 4 ohm Maggie off the ground. Evidently it did come as a surprise to my dealer (a foremost Maggie dealer, at that) because although knowing my amplifiers and having sold them to me), I was advised to buy Tympani III-Bs rather than III-As. As further evidence of their ignorance one of their service workers was sent to my home to look into the problem. Even he didn't understand what was wrong. It took a call from my dealer to Magnepan to inform them as to what was wrong.
IAE, the listener isn't supposed to understand the 'workings' behind one of their speakers anymore than I'm to understand the workings behind my SUV in order to satisfactorily *drive* it.
Some amps which can drive an 8 ohm resistor just fine, do NOT do well at 4 ohms. Like what I understand to be the reality of MOST Home Theater receivers.
Throw in REACTANCE and you are cooked. Even some amps which measure OK as resistance drops fall flat when inductance or capacitance are added, turning resistance into impedance.
I had a Rotel RB1070 of about 135x2 @8ohms and 330 'bridged' into 8. That implied 165x2 @4ohms, but Rotel did NOT list a 4 ohm rating.
Minimal surprise when the amp was utterly incapable of making my panels work well.
Maggies are an EASY load for any competent amp. Most of the line, while certainly of low sensitivity are also of fairly low reactance.
What amp are you talking about that didn't work with your panels?
What did Magnepan tell your dealer?
Too much is never enough
I was driving a Tympani 1C with a pair of bridged ARC D76As. For fun I had an ARC EC-2A cross-over and a GAS Ampzilla II which I could toss into the mix, naturally with ARC tubed amps on the top, and the SS Ampzilla on the bottom. The afforded power was more than enough. Going into Tympani IIIAs, and with an ARC EC-4, I would have easily been able to tri-amp them. However my dealer suggested the newer IIIBs and I went along with his advice. None of my amps, and in any combination could drive any panel within a IIIB.
I wasn't party to the conversation between my dealer and Magnepan. (Why do you even think I could/would have been in on it? I let them resolve it as best as they saw fit.)
The Reason? Let's see. My speakers don't work properly with the amps my dealer recommended. So, they talk to the manufacturer of the speaker? Right so far? How could you NOT want to know what the verdict is?
In the end YOU'VE got a bad speaker / amp mismatch, not the dealer OR Magnepan.What was the crossover point when you used the Ampzilla / D76a combo?
And, is THIS the Ampzilla you had or a newer version? This, the original I guess, had NO 4 ohm rating. So, it's no surprise to find it falling flat into a low impedance load.
The II version was also 200 @8 and I didn't see a 4 ohm for that one, either.I just looked up another in the LONG line of 'ampzilla' product. The Son Of Ampzilla II is rated at 220x2 into 8ohms and 350x2 into 4ohms. I see NO REASON for THAT version of the AmpZilla to be in the LEAST inadequate when running either side of low sensitivity panels.
Too much is never enough
Edits: 08/10/15
"The Reason? Let's see. My speakers don't work properly with the amps my dealer recommended. So, they talk to the manufacturer of the speaker? Right so far? How could you NOT want to know what the verdict is?
In the end YOU'VE got a bad speaker / amp mismatch, not the dealer OR Magnepan."
You may not be as clever as you think because until 1977 Magneplanar speakers were marketed by ARC, so it seemed a natural to discuss the problem with either Magnepan, ARC, or both. My dealer contacted (either of them?) because he was one of their prime dealers, and selling both of them. Obviously he needed more information, and not solely to accommodate me.
The ARC EC2A (1972-1977) was delivered set to 100Hz, for use with the then Tympani system.
Thanks for the information you found. Nonetheless at one time I owned both the original Bongiorno GAS Ampzilla and an Ampzilla IIi. (Unlike the 'i' in 3.7i, that "i" stood for industrial. By the time of the Ampzilla II's release, Mr. B was no longer associated with GAS.)
Unlike other listeners back then I couldn't hear anything special in driving my Tympani 1Cs using ARC tubed amp products, (e.g. the D-76As), so I had those SS Ampzillas on hand. You needn't inform me as to the 'Zilla's ability to drive any section of a Tympani IIIB. Neither my dealer's installation crew (being part of his service department) nor I found them compatible with the IIIBs sold to me, and he took them back refunding all my costs.
For all I knew during that time, my dealer may not have been completely honest with me. Perhaps he couldn't any longer get his hands on a Tympani III(A), and not wanting to lose a sale he convinced me to purchase the III-B. That was unfortunate because at that time I also had a ARC EC4a (1974-1977) on hand, and the amplifiers useful for tri-amping a Tympani III(A).
Quite aware of the marketing of the Tympani speakers.
I've been a Maggie OWNER for probably about 35 years now, starting with some 'used' MG-1 panels which I found so amazing as to get me to sell my JBL 4311 'clones' from RSL, a SoCal 'boutique' brand of good reputation.
If, as I'm lead to believe the ARC 76a is an 'improved' version of the ARC 75 than No Wonder it wouldn't work WELL with your panels. Even one section. 75 or so a side is very much on the low end while IF the speakers were in an appropriately sized space, that would up the power needed even MORE. After all, my 5000 cubic foot room is ill-shaped and maybe not large enough for such large panels. I MIGHT be ok with 3-series.
100hz Crossover? That is probably around 20%:80% range for required power. BUT, bass has some high power peak demand so I wouldn't count on getting away with such low power on the bottom end.
And Yes, 'rumor has it' that ARC and Maggie go well together. Perhaps some OTHER mitigating factor? Setup? Room condition? Size of room or dimensional ratio? REALLY bad power? Some kind of CABLE or IC issue?
And as a total aside, I friend down here in SoCal, and a poster here on AA, owns a pair of 20s. He Biamps using Emotiva amps on the bottom and tubes on top. And Man, did this sound GOOD. REAL GOOD. I think he uses a Marchand crossover. Also, since the last time I heard 'em, the tubes have been replaced with some SS amps.
And you can BET that if my dealer was talking to the manufacturers of my stuff ABOUT my setup and problems, I'd really WANT to be part of the discussion, even if only at the 'fly on the wall' level.
And I'll stand by what I said. At the END OF THE DAY, no matter WHAT went on with the dealer and Magnepan YOU are the one with the problem.
I know from my experience using a non-4ohm rated amp that I'll NOT be doing that again. Ever. It's not like in that time frame that 4ohm speakers were unknown, either. I think the AR3a was a 4 ohm speaker? And pretty popular at the time.
And of course, your dealer SHOULD have benefitted from such a conversation. No question about it. Even then, I'm sure Magnepan knew things about THEIR panels that others didn't.
So, how'd this all shake out? I think that's the important thing.
Too much is never enough
Pictureguy, I wrote in my last post telling how it all shook out:
" Neither my dealer's installation crew (being part of his service department) nor I found them compatible with the IIIBs sold to me, and he took them back refunding all my costs."
(The first above "them" meaning any and all the amplifiers I bought from him.)
Perhaps a bit of a run-on sentence, causing you to miss it.
Yes, I read but apparently didn't exactly Comprehend! I've got CRS. Your writing is FINE, especially compared with some folks who have grammar problems compounded by spelling problems in addition to structural issues.
But, what amp DID you end up with? Did you try some other crossover or settings? How about one BIG amp like maybe the Magtech? If I had VERY deep pockets, I'd have a PAIR of Pass Labs XA30.5 with one per speaker.
Just for a point of reference, I OWNED a Rotel RB1070 which proved unable to drive my panels. I than got a PSAudio GCC250 'd' amp (integrated) which took years to become unsuitable. And I went thru MORE setup hassles with my Panels than in the previous 2 1/2 decades TOGETHER. Finally got it ok, but decided to go to a PAIR of Parasound A23 of 200x2 @4ohms. ONE per panel. This is good and allows a Path Forward since I'd love to go to a PLLXO. The P5 'matching' preamp will easily support this idea. And, it's possible to pretty much duplicate the crossover the speaker came with. But on a board which will EASILY fit into an Altoids tin.
I'm glad to hear of another dealer which 'stepped up'. Too bad, too, you went thru such hassles with amp choice. I've owned a bunch of different stuff over the years, too, starting with a Kenwood Integrated a long time ago.
Too much is never enough
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